Most of the Wikipedia articles on technical subjects, and especially on mathematical topics, are terrible as introductory exposition. They are jargony, highly technical, and self referential. They usually contain much that is irrelevant, and they almost never properly explain the context for an idea.

The main problem is that Wikipedia articles are tiny and atomic, so it’s difficult to synthesize and organize ideas into a coherent story. The culture of Wikipedia frowns on the kind of exposition found in textbooks or lectures. And perhaps most importantly, no one is responsible for either individual articles or sets of related articles in a field. Working within those confines is not the best way to spend your time if the goal is to give future generations a leg up, in my opinion.

If you want to learn about mathematics, even a mediocre textbook is nearly always better than the relevant Wikipedia pages. The Wikipedia pages are then useful later, as a reference, for people who already understand their content.